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Old 10-01-10, 08:34 PM   #1
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bicyle frame size help

hey you guys, where do i find the bicycle frame size of my bicycle? is it engraved into the bicycle somewhere? or do i need to manually measure it?
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Old 10-01-10, 10:27 PM   #2
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Measure it. From the center of the crank to the top of the seat tube.
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Old 10-01-10, 11:46 PM   #3
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Bicycle size on a new bike is usually on a sticker on the seat tube.
Road bike sizes are in centimetres.
Mountain bike sizes are in inches.
Some manufacturers use Sm, M, L, XL
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Old 10-02-10, 10:29 PM   #4
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For some reason unknown to me frame manufacturers put the size sticker on top of the clearcoat with a weak adhesive. The typical way to measure is from the center of the crank to where the center of the seattube intersects with the top of the toptube.
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Old 10-03-10, 06:41 AM   #5
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+1 Tape measure.

Many manufacturers (Trek for example), use a removable decal for the sizing, so on used Treks, its often long gone. Sometimes you will find the frame size cast into the bottom bracket shell, but not very often.

If you are comparing with other bikes, just realize some manufacturers measure it differently: center to center, center to top, etc. And in the used bike market (Craigs List for example), most sellers either don't own a tape measure, or can't read one, as I rarely see a bike on C/L with the size accurate. I buy one one or two used bikes a week, so I see a lot of used bikes. Bought two bikes this week, seller stated they were the same size. Actually, one was a 52cm, the other a 56cm. 4 cm is over 1 1/2 inches, so even a yardstick could tell the difference.

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Old 10-03-10, 07:41 AM   #6
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Originally Posted by Laserman View Post
Measure it. From the center of the crank to the top of the seat tube.
That's not the usual way bike sizes are specified. For a level top tube frame the measurement is either from the center of the crank to the top of the top tube or from the center of the crank to the center of the top tube measured parallel to the seat tube in both cases.

For sloping top tube frames, the messurements are to where a "virtual" level top tube would intersect the seat tube.
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Old 10-03-10, 07:37 PM   #7
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Some frames are measured C-C (center of BB to center of ST/TT junction)
Some frames are measured C-T (center of BB to top of either ST/TT juntion or top of seat clamp)

I would suggest going to the manufacturer's website to determine which method they use to measure their frames. Then, take a tape measure and do the same on your frame.
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